Semiconductor optical logic devices (logic gates) and optically or electronically controlled optical switching devices (optical switches) are useful in a variety of contexts, such as telecommunications. These devices typically operate with inputs consisting of a (binary digitally) pulsed control signal (A) and a controlled optical beam (B) which may or may not be pulsed depending upon whether the desired device is an optical logic gate or an optical switch. By "pulsed" it is meant that the control signal at any moment of time can have either of two intensities--typically labeled "zero" and "one" or labeled "low " and "high". In prior art, one form of such an optical switch utilizes an optically active element having the property of delivering the controlled beam B as output to a utilization means when the control signal A is "high" (hereinafter "1"; A=1), and of not delivering the controlled beam B when the control signal A is "low" (hereinafter "0"; A=0) i.e., a positive switch or a logic gate AB or AND, or, in the alternative, of delivering B when A is low (A=0), and not delivering B when A is "high" (A=1),i.e., a negative or inverting optical switch, a logic AB.
In a paper authored by K. Tai et al, published in Applied Physics Letters, vol. 50, pp. 795-797, entitled "1.55 .mu.m Optical Logic Etalon With Picojoule Switching Energy Made of InGaAs/InP Multiple Quantum Wells," an optical switch including an indium phosphide based multiple quantum well structure located in a Fabry-Perot etalon (multiple reflection interfermeter) was disclosed in which the control signal was an opical beam A with a wavelength of about 1.06 .mu.m and the controlled beam B had a wavelength of about 1.55 .mu.m. The purpose of the etalon is to enhance the contrast ratio of the output when the control beam A is present vs. absent, as known in the art.
It would be desirable, however, to increase the switching speed of such devices, in order that they may be more practical for use in fast operating environments, such as high speed digital optical telecommunications and optical logic.